Does thumb sucking damage teeth? Not all thumb sucking results in damage to the teeth or mouth. For example, passively holding the thumb in the mouth doesn’t typically cause damage. However, active thumb sucking with a lot of motion can cause damage to primary (baby) teeth, though this usually corrects itself as the permanent teeth come in. Persistent, vigorous thumb sucking can sometimes cause misalignment of your child’s permanent teeth and affect the jaw or the shape and roof of the mouth. Thumb sucking may also expose your child to dirt, bacteria, and viruses. Studies have found that children who suck their thumbs were less likely to experience allergic reactions to substances such as pollen and dust mites later on in life. So, …